Kruger was an All-conference and preseason All-America quarterback as a senior in 2003 at Timpanogos High School in Orem, Utah.

After an all-conference sophomore season in 2008, he decided to forgo his final two years of college eligibility to enter the 2009 NFL draft.

Source:[2] Kruger redshirted his freshman year of 2004, after which he served a two-year mission in Kansas and Missouri for the Church of Jesus Christ of Latter-day Saints, returning to the football field in the fall of 2007.

Due to an off-field injury (see Personal section), he was held out of spring practices but returned to the field in the fall.

[5] On November 29, 2009, in a game against the Pittsburgh Steelers, Kruger intercepted a Dennis Dixon pass in overtime and returned it 22 yards to set the Ravens up for a game-winning 29-yard field goal by kicker Billy Cundiff.

In addition to this, he also recorded a sack against New England Patriots quarterback Tom Brady in the AFC championship game.

During the Wild Card Round in the 2012 playoffs, he forced Indianapolis Colts quarterback Andrew Luck to fumble.

In the Divisional Round against the Denver Broncos, he recovered a strip sack fumble by Terrell Suggs on quarterback Peyton Manning in which the Ravens would go on to win 38–35 in double overtime.

In Super Bowl XLVII, he had two sacks on critical junctures of the game, forcing the 49ers to kick field goals.

[15] In college at Salt Lake City, Utah (January 29, 2008), a street stabbing left him with a collapsed lung and a 6.5-inch scar on his chest.

A screwdriver was driven through the back of a Ute teammate and brass knuckles were used to break the nose and shatter the cheekbone of his younger brother.

The fight left Kruger with "life-threatening injuries" that required nearly 50 staples to close the incisions made during a four-hour surgery.